The field of the invention is plastic fabricating machinery and the invention relates more particularly to machines used to cut or trim hollow, blow molded, plastic objects.
Many cutting operations require a peripheral cut such as a container with a large opening. Also, it has been recognized that it is often efficient to mold two open-faced parts in a face-to-face relationship and then subsequently cut the two halves apart to form two finished blow molded objects. The blow molding operation leaves an opening at the top of the molded object where the air is injected. For those objects where the opening formed by the blow molding operation must be closed, this step may be cut in half since only one of the two parts will have such an opening. Another advantage of face-to-face molding is that the finished part has essentially no waste except for the tabs.
However, the cutting operation necessary to separate the face-to-face halves must be carefully performed and, if done by hand, is labor intensive and often leads to rejected parts by careless cutting. Also, such repetitive movement has been observed to cause a disease of tendons which can be very painful for those so afflicted. While circular parts are relatively easy to cut in two in an automated operation, rectangular or other irregular shapes have resisted attempts to be automated.